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Loudness decay (fwd)

dybala at utdallas.edu dybala at utdallas.edu
Mon Dec 11 09:30:09 EST 1995


Eric Smith (erc at cinenet.net) wrote:
> In article <199512080614.AAA03993 at curly.cc.utexas.edu>,
> Jeffrey G. Sirianni <sirianni at UTS.CC.UTEXAS.EDU> wrote:
> >Greater decay in the high frequencies indicates a cochlear lesion and not a
> >retrocochlear lesion

> The decay also happened in a promontory stimulation test which was part
> of an evaluation to see if a cochlear implant would be indicated.
> Therefore, the cochlea itself is not the cause of the strange
> symptoms.  It's either the auditory nerve or the brain.

> I wonder if it could somehow be caused by adapting to tinnitus.  Since
> tinnitus tends to sound like a steady tone or other steady sound, could
> it be that the auditory nerve and/or auditory processing in the brain
> has learned to filter out all steady tones and other steady sounds that
> last more than a couple of minutes?  The fact that the sound comes back
> to full loudness instantly if it's interrupted for even a fraction of a
> second seems to support this.

> An MRI is now scheduled, as you suggested.  But so is a cochlear
> implant, a few weeks later, if the MRI doesn't show anything.  With the
> cochlear implant, it might be easier to analyze the strange symptoms,
> assuming they continue then.  In particular, it will be easy to say for
> sure that none of them are caused by hair cells.  But in any case,
> since the problem only happens with steady tones, and not when the tone
> is interrupted, nor with any kind of modulated sound, it's really just
> of academic interest, because in real life there are very few
> situations where anyone wants to listen to a steady tone for more than
> a minute.

> I'm not sure if I mentioned this, but an OAE and brainstem test (BSER)
> showed no response at all.  The BSER used clicks which tested from
> 2000-8000 Hz.  I probably didn't mention these tests because they were
> only done recently, and my last posting on this subject was probably
> before that.

Wouldn't the "retrocochlear lesion" which is causing the "tone
decay" be a contraindiaction for a cochlear implant?

As far as the tinnitus theory, does the pt have tinnitus because
if they do, that would mean that the brain does not have
the ability to "filter out steady tones"  in that
if it could it would filter out the tinnitus.

If there is such a thing as adapting to tinnitus (besides
masking it externally) it is usually
due to the fact that other symptoms that a patient
has ex:depression, anxiety, high blood pressure,
etc., are causing the "perception" that the tinnitus is louder
when the loundness matched sensation level of the T has not
changed.  So when the other symptoms have been addressed
the perceived T is not as annoying but the SL of the match is
the same.

Why are you getting a cochlear implant?
I remember seeing the org post but I don't
remember the amout of loss etc.

-- 
Thank you for your support,
Paul Dybala
dybala at callier.utdallas.edu
dybala at utdallas.edu



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